diff --git a/pkg/tui/cart.go b/pkg/tui/cart.go
index 06e0970..082b8f5 100644
--- a/pkg/tui/cart.go
+++ b/pkg/tui/cart.go
@@ -33,7 +33,8 @@ func (m Model) generateCartContent() string {
 			Align(lipgloss.Center).
 			Width(m.widthContent).
 			Padding(2, 0)
-		return emptyStyle.Render("Your cart is empty\n\nPress s to go back to shop")
+		render := emptyStyle.Render("Your cart is empty\n\nPress s to go back to shop")
+		return render
 	}
 
 	cartItems := ""
@@ -148,7 +149,8 @@ func (m Model) CartUpdate(msg tea.Msg) (Model, tea.Cmd) {
 		cartItems := m.GetCartItemsSlice()
 		if m.cart.cursor >= 0 && m.cart.cursor < len(cartItems) {
 			cartItems[m.cart.cursor].Quantity++
-			return m, m.syncCartItemCmd(cartItems[m.cart.cursor].CoffeeID, cartItems[m.cart.cursor].Quantity)
+			m, cmd := m.syncCartItemCmd(cartItems[m.cart.cursor].CoffeeID, cartItems[m.cart.cursor].Quantity)
+			return m, cmd
 		}
 	case "-", "_":
 		cartItems := m.GetCartItemsSlice()
@@ -165,7 +167,8 @@ func (m Model) CartUpdate(msg tea.Msg) (Model, tea.Cmd) {
 				}
 				newQty = 0
 			}
-			return m, m.syncCartItemCmd(coffeeID, newQty)
+			m, cmd := m.syncCartItemCmd(coffeeID, newQty)
+			return m, cmd
 		}
 	case "p", "enter":
 		if !m.IsCartEmpty() {
diff --git a/pkg/tui/model.go b/pkg/tui/model.go
index e01adfc..698bab8 100644
--- a/pkg/tui/model.go
+++ b/pkg/tui/model.go
@@ -346,7 +346,7 @@ func (m Model) checkoutStep() int {
 
 // updateLayout recalculates all layout variables from the raw viewport dimensions.
 // This should be called whenever the terminal is resized.
-func (m *Model) updateLayout(width, height int) {
+func (m Model) updateLayout(width, height int) Model {
 	m.viewportWidth = width
 	m.viewportHeight = height
 	switch {
@@ -369,6 +369,7 @@ func (m *Model) updateLayout(width, height int) {
 	}
 
 	m.widthContent = m.widthContainer - 2
+	return m
 }
 
 // ProductsMsg is sent when products are fetched from API
@@ -646,15 +647,15 @@ func (m Model) checkoutWithSavedCard() tea.Cmd {
 	}
 }
 
-func (m *Model) syncCartItemCmd(coffeeID uint, quantity int) tea.Cmd {
+func (m Model) syncCartItemCmd(coffeeID uint, quantity int) (Model, tea.Cmd) {
 	if m.APIClient == nil || m.User == nil {
-		return nil
+		return m, nil
 	}
 
 	updateID := time.Now().UTC().UnixMilli()
 	m.lastCartUpdateID = updateID
 
-	return func() tea.Msg {
+	return m, func() tea.Msg {
 		cart, err := m.APIClient.SetCartItem(coffeeID, quantity)
 		return CartSyncedMsg{
 			UpdateID: updateID,
@@ -748,10 +749,10 @@ func (m Model) saveCardOnlyCmd(form PaymentFormCompleteMsg) tea.Cmd {
 
 // loadCartFromAPI populates the in-memory cart map from an API CartData response
 // It matches cart items to local Coffees by ID so the Coffee struct is populated
-func (m *Model) loadCartFromAPI(cartData *api.CartData) {
+func (m Model) loadCartFromAPI(cartData *api.CartData) Model {
 	m.Cart = make(map[uint]*models.CartItem)
 	if cartData == nil {
-		return
+		return m
 	}
 
 	for _, item := range cartData.Items {
@@ -765,14 +766,15 @@ func (m *Model) loadCartFromAPI(cartData *api.CartData) {
 	if m.cart.cursor >= len(m.Cart) {
 		m.cart.cursor = 0
 	}
+	return m
 }
 
 // GetCartItemsSlice converts the cart map to a sorted slice for consistent iteration.
 func (m Model) GetCartItemsSlice() []*models.CartItem {
 	// Get keys and sort them for stable ordering
 	keys := make([]uint, 0, len(m.Cart))
-	for key := range m.Cart {
-		keys = append(keys, key)
+	for cartKey := range m.Cart {
+		keys = append(keys, cartKey)
 	}
 
 	// Sort keys to ensure consistent order
@@ -780,8 +782,8 @@ func (m Model) GetCartItemsSlice() []*models.CartItem {
 
 	// Build items slice in sorted order
 	items := make([]*models.CartItem, 0, len(m.Cart))
-	for _, key := range keys {
-		items = append(items, m.Cart[key])
+	for _, cartKey := range keys {
+		items = append(items, m.Cart[cartKey])
 	}
 	return items
 }
@@ -890,7 +892,7 @@ func newModelWithRenderer(username string, renderer *lipgloss.Renderer) Model {
 		APIClient: api.NewClient("http://localhost:8080", ""),
 		FAQs:      LoadFaqs(),
 	}
-	m.updateLayout(120, 30)
+	m = m.updateLayout(120, 30)
 	return m
 }
 
diff --git a/pkg/tui/payment_form.go b/pkg/tui/payment_form.go
index d96527e..6d388a5 100644
--- a/pkg/tui/payment_form.go
+++ b/pkg/tui/payment_form.go
@@ -370,7 +370,7 @@ func (m Model) renderPaymentHttpsView() string {
 		return baseStyle.Render("  generating payment link...")
 	}
 
-	qr, qrSize, err := qrfefe.Generate(0, *m.payment.collectURL)
+	qr, qrSize, err := qrfefe.Generate(*m.payment.collectURL)
 	if err != nil || qrSize > m.widthContent {
 		// QR too wide for the terminal — just show the URL.
 		return baseStyle.Render("open in browser to add payment information:") + "\n\n" +
diff --git a/pkg/tui/shop.go b/pkg/tui/shop.go
index 52ec23f..33c6038 100644
--- a/pkg/tui/shop.go
+++ b/pkg/tui/shop.go
@@ -180,7 +180,8 @@ func (m Model) ShopUpdate(msg tea.Msg) (Model, tea.Cmd) {
 			} else {
 				m.Cart[coffeeID] = &models.CartItem{CoffeeID: coffeeID, Coffee: coffee, Quantity: 1}
 			}
-			return m, m.syncCartItemCmd(coffeeID, m.Cart[coffeeID].Quantity)
+			m, cmd := m.syncCartItemCmd(coffeeID, m.Cart[coffeeID].Quantity)
+			return m, cmd
 		case "-", "_":
 			coffeeID := coffee.ID
 			if item, exists := m.Cart[coffeeID]; exists {
@@ -190,7 +191,8 @@ func (m Model) ShopUpdate(msg tea.Msg) (Model, tea.Cmd) {
 					delete(m.Cart, coffeeID)
 					newQty = 0
 				}
-				return m, m.syncCartItemCmd(coffeeID, newQty)
+				m, cmd := m.syncCartItemCmd(coffeeID, newQty)
+				return m, cmd
 			}
 		}
 	}
diff --git a/pkg/tui/update.go b/pkg/tui/update.go
index 14a4cbd..33e8675 100644
--- a/pkg/tui/update.go
+++ b/pkg/tui/update.go
@@ -13,7 +13,7 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	// Resize debounce tick, must fire before page dispatch
 	if tick, ok := msg.(resizeTickMsg); ok {
 		if tick.seq == m.resizeSeq {
-			m.updateLayout(m.pendingWidth, m.pendingHeight)
+			m = m.updateLayout(m.pendingWidth, m.pendingHeight)
 			switch m.currentPage {
 			case shopPage:
 				m = m.updateShopViewports()
@@ -97,7 +97,7 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			m.Username = u.Name
 		}
 		cart := &api.CartData{Items: msg.Data.Cart}
-		m.loadCartFromAPI(cart)
+		m = m.loadCartFromAPI(cart)
 		m.SavedAddresses = msg.Data.Addresses
 		m.SavedCards = msg.Data.Cards
 		m.Orders = msg.Data.Orders
@@ -112,7 +112,7 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			return m, m.fetchCartCmd
 		}
 		if msg.UpdateID == m.lastCartUpdateID {
-			m.loadCartFromAPI(msg.Cart)
+			m = m.loadCartFromAPI(msg.Cart)
 		}
 		return m, nil
 	case tokenRefreshTickMsg: